Short wave oscillator



Nov. 10,1936. H.- N. ROZANOWSKI 2,060,508

' SHORT WAVE OSCILLATOR Original Fi led Oct 3, 1931 WITNESSES: INVENTORI I 7 I Henry Jiozdnowsfi'.

I A I J ATTOi2NE Patented Nov. 10, 1936 PATENT OFFICE SHORT WAVEOSCILLATOR Henry N. Kozanowski, Wilkinsburg, Pa., assignor toWestinghouse Electric & Manufacturing Company, a corporation ofPennsylvania Application October 3, 1931, Serial No. 566,604 RenewedAugust 30, 1934 10 Claims.

My invention relates to high frequency oscillators of the Barkhausentype for producing exceedingly high frequency oscillations.

In the Barkhausen oscillator, the control grid of a three-element tubeis maintained at a positive potential, while the plate is maintained ateither a low positive potential or at a negative potential. It isbelieved that this type of oscillator functions in the following manner:

The positive grid attracts the electrons and accelerates them to a speedsufiicient to make them pass through the mesh of the grid into thenegative field between the grid and the plate. The negative field slowsup the electrons and causes them to move back in the opposite direction,so that they again pass through the mesh of the grid. In this Way, theelectrons oscillate about the grid, the grid remaining at asubstantially constant potential.

While it has been possible to generate currents of a very high frequency(having wave lengths of the order of 90 cms.) by means of this type ofoscillator, it has been very diflicult to obtain a satisfactory poweroutput. Also it has been difficult to make an oscillator function atwave lengths much lower than 90 cms.

One object of my invention is to provide an oscillator of theabove-mentioned type which will give a large power output.

Another object of my invention is to provide an oscillator that willoscillate at lower wave lengths than previously known oscillators of theabove-mentioned type.

Still another object of my invention is to provide an oscillator of theabove-mentioned type in which the frequency is substantially independentof variations in the voltage applied to the tube.

In practicing my invention, I employ two vacuum tubes which have theirgrids connected together and connected to a source of positivepotential. The plates of the tubes are connected to a pair of Lecherwires, While the filaments are connected to a second pair of Lecherwires which are positioned parallel to the first pair. Formerly, thegrids instead of the filaments were connected to the second pair ofLecher wires.

Other features and advantages of my invention will appear from thefollowing description taken in connection with the accompanying drawing,in which Figure 1 is a circuit diagram of an oscillator constructed inaccordance with my invention.

Fig. 2 is a view showing the physical arrangement of the Lecher wires.

Fig. 3 is a view illustrating the manner in which the Lecher may be madeadjustable. I Referring to the drawing, the oscillator comprises avacuum tube 10 having a cathode II, a grid l2 and a plate I3 and avacuum tube I4 having a cathode [5, a grid l6 and a plate ll. Thefilaments are heated from a 110 volt line by means of a step-downtransformer l8 which has the mid-point of its secondary winding l9grounded. The filament ll of the tube i0 is negative terminal of thesource of potential is grounded. With the oscillator adjusted tooscillate at 60 cms. a grid potential of 500 volts has been foundpreferable. If desired, the choke coil 21 may be omitted, since thegrids l2 and 5 are at substantially zero radio frequency potential.

The plates l3 and I! are connected to the conductors 28 and 29,respectively, of the first pair of Lecher wires. The ends of these wiresremote from the tubes are electrically connected through a conductor 30,a low resistance meter 3| and a conductor 32.

The conductors 2B and 29 are connected through the chokes 33 and 34,respectively, to the negative terminal of a source of potential 35. Thepositive terminal of the source is connected to ground. With theabove-mentioned adjustment for operation at 60 cms., a negativepotential of 110 volts on the plate was found desirable. One of thechoke coils 33 and 34 may be omitted, but it is preferred to employ bothof them in order to make the circuit symmetrical.

The filaments H and I5 are connected to the conductors 36 and 31,respectively, of the second pair of Lecher wires through couplingcondensers 38 and 39. mote from the tubes are electrically connectedthrough a conductor 40.

The condensers 38 and 39 may be omitted and. the Lecher wires 36 and 31connected directly to the filaments II and I5, providing they areconnected to points on the filaments that are at the same potential. Forexample, the condensers 38 and 39 could be omitted and the Lecher wire36 connected to the point X on the filament II and the Lecher wire 37connected! The ends of the conductors reill to the point Y on thefilament I 5. It will be noted that points X and Y are connected to thesame terminal of the secondary l9.

The use of the filament resistor 22 is important, because it isdiiiicult to obtain two tubes having filaments which have the sameelectron emitting characteristics. This is especially true of vacuumtubes which have thoriated tungsten filaments. In the Barkhausenoscillator, the grids are maintained at such a high positive potentialthat the tubes operate at almost their saturation current value. Since,in this case, a grid will remove practically all of the electrons fromthe filament that the filament is capable of emitting, the tube havingthe best electron emitting filament will become overheated, while theother tube will remain cool. In my circuit, I place the resistor 22 inseries with the filament having the best electron emittingcharacteristics, so that the filament may be operated at .a lowertemperature to reduce its electron emissivity. In one embodiment of myinvention the tubes employed were UX 852 tubes.

The relative location of the Lecher wires is illustrated in Fig. 2. Itwill be noted that one pair of Lecher wires is placed directly above theother pair whereby both pairs of wires are electrically coupled to eachother. These wires or conductors are preferably of copper tube 4! havingtelescoping joints so that the length of the conductors may be adjusted.Each conductor is adjusted so that it is about one wavelength long.

It has been found that, by employing two vacuum tubes of a given size inthe manner described above, the output of the oscillator is much morethan double the output of any known oscillator of this type employing asingle tube of the same size.

It may be noted that the output of my oscilator may be modulated byvarying the plate voltage as shown diagrammatically by the element 42.

The frequency at which the oscillator operates is determined by thelength of the plate Lecher wires, while the length of the filamentLecher wires controls the amplitude of the oscillations.

' The grid and plate voltages may be varied within wide limits and thefrequency remains at the value determined by the plate Lecher wires.This is in marked contrast to the behavior of other Barkhausenoscillators.

Various modifications may be made in my invention without departing fromthe spirit and scope thereof, and I desire, therefore, that only suchlimitations shall be placed thereon as are imposed by the prior art andare set forth in the appended claims.

I claim as my invention:

1. An oscillator comprising two vacuum tubes, each tube having acathode, an anode, and a grid, means for connecting said grids togetherelectrically, means for maintaining said grids at a positive potentialwith respect to said cathodes, a pair of Lecher wires and means forconnecting them to said cathodes, a second pair of Lecher wirespositioned substantially parallel to said first pair and connected tosaid anodes said pairs of Lecher wires being coupled, and means forapplying a potential to said anodes lower than one of said pairs ofLecher wires, said anodes being connected to the other of said pairs ofLecher wires, means for applying potentials to said cathodes and anodes,means for electrically connecting said grids and means for maintainingthem at a higher potential with respect to said cathodes than saidanodes.

3. An oscillator of the Barkhausen type comprising a pair of vacuumtubes, each having a cathode, a grid and an anode, means for maintainingsaid grids at a positive potential with respect to said cathodes, meansfor maintaining said anodes at a negative potential with respect to saidcathodes, a pair of oscillatory circuits, means for coupling said anodesto one of said circuits, means for coupling said cathodes to the otherof said circuits, said pairs of oscillating circuits being electricallycoupled to each other.

4. An oscillator of the Barkhausen type comprising a pair of vacuumtubes, each having a cathode, a grid, and an anode, means formaintaining said grids at a positive potential with respect to either ofsaid cathodes, means for maintaining said anodes at a negative potentialwith respect to said cathode, a pair of Lecher wires connected to saidcathodes and a second pair of Lecher wires connected to said anodes,said pairs of Lecher wires being electrically coupled.

5. An oscillator of the Barkhausen type comprising two vacuum tubes,each having a cathode, a grid, and an anode, means for maintaining saidgrids at a positive potential with respect to either of said cathodes,means for maintaining said anodes at a negative potential with respectto said cathodes, a pair of Lecher wires coupled to said anodes, a pairof Lecher wires coupled to said cathodes, said first pair beingelectrically coupled to said second pair, and means for separatelycontrolling the amount each cathode is heated.

6. An oscillator comprising two electric discharge tubes spaced apartfrom each other, each having a cathode, a grid and an anode, a pair ofcoupled conductors extending each from one of said anodes in asubstantially parallel relationship and having distributed capacity, asimilar pair of conductors connected to said cathodes, means formaintaining a potential difference between the cathode and anode of eachof said electric discharge tubes, a further conductor materially shorterin length than either of said two conductors interconnecting the gridelectrodes of said tubes and means for maintaining a higher potentialdifference than that above-mentioned, between the grid electrode and thecathode of each said electric discharge tubes.

7. An oscillator comprising two electric discharge tubes spaced apartfrom each other, each having a cathode, a grid and an anode, twoconductors, each of which is substantially longer than the distanceseparating said vacuum tubes,

of wires connected to said anodes and coupled to each other bothmagnetically and electrostatically to constitute a Lecher system,electrical connections between said grids, a pair of wires similarlycoupled and connected to said cathodes to constitute a second Lechersystem, means for electrically connecting said pair of anode LecherWires, said pair of cathode Lecher wires and said grid interconnectionto each other to complete circuits between said electron dischargetubes, and means for impressing a positive potential on said gridelectrodes relative to both said cathodes and anodes.

9. An oscillator comprising two electric discharge tubes spaced apartfrom each other, each having a cathode, a grid and an anode, threeconnections each joining an electrode of one tube with the correspondingelectrode of the other tube, at least one of said connections comprisingsubstantially parallel coupled conductors having distributed capacityand constituting in itself a Lecher system, the connection joining saidcathodes being parallel along its length to said Lecher system, andmeans for placing the grid electrodes at a positive potential relativeto said anodes and cathodes.

10. An oscillator comprising two electric discharge tubes spaced apartfrom each other, each having a cathode, a grid and an anode, threeconnections each joining an electrode of one tube with the correspondingelectrode of the other tube, the connection joining the cathodes witheach other comprising substantially parallel coupled conductors havingdistributed capacity and constituting a Lecher system and the connectionjoining the anodes with each other also constituting a similar Lechersystem, and means for placing the grid electrodes at a positivepotential relative to said anodes and cathodes.

HENRY N. KOZANOWSKI.

